1. Field of the Invention
The present invention relates to a camera device and a projector device, especially relates to a camera device and a projector device having a protective lens.
2. The Prior Arts
As the image capturing technology advances, the conventional film camera devices have been replaced by digital cameras, and as the resolution of the digital cameras enhances, the size of the sensing components also becomes smaller. The unit pixels of sensing elements (such as charge-coupled device, CCD, or complementary metal-oxide-semiconductor, CMOS) are arranged in arrays. When the object being filmed has a regular spatial frequency, and when the spatial frequency is larger or equal to half of the sampling frequency of sensing elements, aliasing effect can occur, and further causing the phenomenon of moiré patterns. This effect is not seen in the conventional film camera. The moiré patterns are most likely to be seen in the pictures taken by low grade digital cameras, especially when the objects being filmed are hair or neckties with diagonal stripes. When filming such objects, moiré patterns are more likely to occur in the detailed portion of the picture, thereby resulting in defects or color differences in a photo.
In order to solve the abovementioned problems, quartz is usually used as a birefringent crystal to refract light within the light path in a conventional camera device. The quartz utilized generates two refracted light beams with a difference in their optical path, and the two refracted light beams enter its corresponding unit pixel respectively to eliminate the aliasing effect. However, the quartz has a relatively low rigidity in comparison to sapphire, therefore is not suitable to be placed outside the lens. Besides, placing the quartz in the light path can result in a bulky camera device; therefore, it is only used in the high-end SLR cameras or high-end digital cameras.
FIG. 1 is the schematic view illustrating a conventional high-end digital camera device 10. As shown in FIG. 1, the conventional high-end digital camera device includes an optical lens 101, a reflex lens 102, a lens shutter 103, a low pass filter 104, a CMOS image sensing component 105, an image processing module 106, and a liquid crystal display (LCD) 107. The low pass filter 104 also includes a first birefringent lens 1041, a second birefringent lens 1042 and an infrared filter 1043 to block the infrared ray.
The light 14 reflected by an object 12 enters the optical lens 101, and then is reflected by the lens shutter 103 to enter the reflex lens 102. The direction of the light path of the light 14 is then changed, so the direction of the imaging of the object 12 is corrected. When the operator finishes the focusing and setting up the shutter time and the aperture size, the shutter button is pushed to open the lens shutter 103, so that the light 14 can pass through and reaches the low pass filter 104 and sensing component 105 in the rear end. Upon receiving, the sensing component 105 transforms the light 14 into a digital signal, and then the digital signal is processed by the image processing module 106 to output an image to the LCD display 107 for displaying.
In FIG. 1, the first birefringent lens 1041 and the second birefringent lens 1042 are made with quartz, and each lens only has a single light axis. When the light 14 enters the first birefringent lens 1041 and the direction of the light path is not parallel to the single light axis of the first birefringent lens 1041, two refracted light are formed. One of the refracted lights is refracted according to the law of refraction, and is called the ordinary light. The other one of the refracted lights is not refracted according to the law of refraction, therefore is called the extraordinary light. The light 14 is refracted into two parallel lights via the first birefringent lens 1041, so two images offset from each other are formed. Similarly, each of the parallel light is again refracted into two parallel lights via the second birefringent lens 1042, thereby forming more offset images. For the matter of convenience, the ordinary light refracted by the first birefringent lens 1041 is shown as broken lines that are parallel to the light 14 in FIG. 1. The infrared filter 1043 is usually made from a blue glass containing cobalt. The surface of the blue glass is electroplated to block the infrared ray, so as to serve as an infrared filter. Most of the small cameras are not equipped with such components as the infrared filter 1043 because only the high-end cameras have the space and the cost to do so. The low pass filter 104 shown in FIG. 1 is one of the various forms. The optical low pass filter 104 can also be one with single-lens or multiple lenses.
FIG. 2 is a schematic view illustrating a conventional liquid crystal projector device 20. The conventional liquid crystal projector device 20 includes a light source assembly 201, a condensing lens 202, a liquid crystal assembly 203, a color filter 204, a ¼ wavelength polarizer 205 and 207, birefringent crystal 206 and 208, and lens assembly 209. The light beam 210 illuminated by the light source assembly 201 enters the condensing lens 202, and is condensed to a certain area. The condensed light beam 210 then enters the liquid crystal assembly 203, which has multiple unit pixels, in which, the brightness of each of the unit pixels is controlled by a control signal (not shown). After the liquid crystal assembly 203 adjusted the brightness of the light beam 211, the light beam 211 then enters the color filter 204, which controls the color of each unit pixel. The delicacy of the color depends on the size of the unit pixel, where the smaller the unit pixels are, the higher the quality of the color becomes.
After passing through the color filter 204, the light beam 211 enters the ¼ wavelength polarizer 205 so as to be transformed into a polarized light beam 213. The polarized light beam 213 then enters the birefringent crystal 206, and is refracted into a birefringent light beam 214. The birefringent light beams 214 are the ordinary light and extraordinary light, which are parallel to each other. Next, the birefringent light beam 214 enters another ¼ wavelength polarizer 207 so as to be transformed into another polarized light beam 215. The polarized light beam 215 then enters yet another birefringent crystal 208, and is refracted into another birefringent light beam 216. With the birefringence property, the birefringent crystal 206 is designed in such a manner that the difference in the optical path created is equal to the distance between the unit pixels, and so is the birefringent crystal 208. In this way, a unit pixel is split into two or four unit pixels to enhance the output image. At last, the birefringent light beam 216 is projected onto a screen 218 via the lens assembly 209 to enlarge the final image.
The birefringent crystal 206 and 208 utilized in the conventional projector eliminates the aliasing effect and hence improves the moiré patter with its birefringence characteristics. The ¼ wavelength polarizer is also used to form the polarized light or to filter the reflected light with its polarizing characteristics. However, just like the first birefringent lens 1041 and the second birefringent lens 1042 in FIG. 1, the birefringent crystal 206 and 208 and the ¼ wavelength polarizer 205 and 207 are not easy to fit into the device when manufacturing the projectors with smaller sizes. The birefringent crystal 206 and 208 and the ¼ wavelength polarizer 205 and 207 are also not suitable to be placed outside the projector due to its low rigidity. Therefore, a new product, which has a smaller size while having all the above advantages is yet to be developed; such new product can be installed in a slim and light camera device or projector device to solve the drawbacks of the conventional devices.